Automotive vehicles seats are commonly provided with motor-driven seat assemblies and a memory module that has one or more seat position registers for storing the seats' current positions. In the prior art, such memory modules may have been used, when activated, in an attempt to return vehicle seat assemblies to stored seat positions. A stored seat position may, for example, be one that corresponds to a particular seat occupant's preferences, physical characteristics (e.g., height), etc.
Motors have previously been used to drive such seat assemblies, and to drive other vehicle (as well as non-vehicular) components. In the prior art, Hall-effect sensors may have been used in such motors in an attempt to accurately record the actual position of the driven component at any particular time. With every motor revolution occurring in such a prior art system (or more particularly, with every rotation of a rotor within the prior art motor), a pulse signal may have been generated by a Hall-effect sensor built into the motor (e.g., a DC motor). In the prior art, when a pulse signal was detected by the memory module, the data stored in its seat position register it may have been adjusted. Thus, when activated, prior art memory modules may heretofore have used a stored count of (rotor position) pulse signals in an attempt to return a vehicle seat assembly to the stored seat position.
Other prior art systems, which do not use Hall-effect sensors, that have been sought to be used to similar effect may have included ripple-counting based systems. Such systems may have counted modulation (or “ripple”) signals that occur in the current during commutation.
Now, it may generally be thought, though it is not essential to the working of the present invention, that a pulse signal conveyed by a Hall-effect sensor (or a ripple signal that is counted by a ripple-counting based system) corresponds to a specified amount of rotation (or partial rotations) of the motor's rotor. It should, however, be appreciated that these signals do not include any information about motor rotary direction. Rotational counting errors may have arisen from this fact and from the fact that all rotational counts may heretofore have been incrementally added to the count register according to the direction (polarity) of the voltage or current that was applied to the drive motor.
Notably, however, both of these prior art systems may have been subject to the same general types of problems, insofar as they may have generated (and accumulated) positional errors in their count. These positional errors in the count may have been known to occur with increased frequency when a seat or other driven component encounters an obstacle.
Where the motion of the driven component, or of the drive motor, is stopped because of a mechanical stop or obstacle, the force on the system may be released in a manner that is similar to the recoil force of a spring. That is, encountering a mechanical stop or obstacle may cause the drive motor to rotate in a direction that is opposite to that which might be indicated by the supplied polarity of the voltage or current.
Prior art position registers may have failed to account for this sudden change of direction, and any additional (reverse-direction) rotations may have been recorded, and accumulated, in the prior art position registers as being rotations in the original rotational direction. At least in this manner, prior art memory modules may been subject to the introduction of count errors into their position registers.
In fact, these errors may have accumulated in the prior art memory modules' position registers so rapidly that the count error might reach to noticeable levels after only a few (or several) cycles. It may be generally thought, though it is not essential to an understanding of the present invention or its workings, that benchmark data in this regard may be available.
These positional errors in prior art systems may have generally tended to accumulate over time and to have caused the recorded seat (or other component) position to vary from its actual position. Inaccurately recorded positions for the seats relative to the steering column, pedals, and mirrors may have generally tended to result in customer irritation and/or in reduced safety. Of course, memory modules for motor-driven adjustable mirrors, pedals, and/or steering columns may have been subject similar problems.
It is notable that persons having ordinary skill in the art may have been previously thought that, when a drive motor was energized with a certain polarity of voltage, it would only rotate in a certain rotational direction. Previously, it may also have been generally thought that, even after the supply of power to the drive motor had been cut off, the motor would continue to rotate in same direction (i.e., the direction of its rotation whilst being powered) on account of inertial effects. That is, it may have been previously thought by persons having ordinary skill in the art that, after a voltage of a known polarity was supplied to a drive motor, all rotor position signals that were thereafter received (whether from a connected Hall-effect sensor or ripple signals that were counted in ripple-counting based system) were indicative of that drive motor's rotor movement in a single rotational direction—i.e., at least until a change in voltage polarity was detected.
Moreover, a corresponding rotational count (indicative of a single rotational direction) may previously have been added to the respective seat position register in prior art memory modules. That is, when power to prior art drive motor was switched off, the counting of revolutions continued in the same direction.
The aforementioned prior art systems may, however, have relied upon an untrue assumption in so adjusting the data stored in the seat position register—i.e., without recognizing that, regardless of the voltage polarity and voltage value between the two terminals of a motor, either of two possible rotary directions (clockwise or counterclockwise) may be possible.
Recently, some OEMs may, in an attempt to avoid some of the aforementioned problems in the prior art, have been reticent (or may have even outright refused) to use Hall-effect sensor based systems.
Now, although prior art memory module suppliers may have developed various attempted solutions to address the issue of accumulated count errors, to date, none of these rudimentary attempts have been particularly satisfactory (perhaps least of all to the end users).
One rudimentary attempt to solve the perceived problems that may be generally well-known may have been to automatically have the memory module move the seat to an end stop reference position after every 100 (or 200) motor motions, i.e., so as to reset the seat position register. This “reset” technology may have attempted to guarantee that the accumulated position error will not exceed a certain value. However, in attempting to solve one problem, this methodology may actually have caused a number of other problems. For example, if a passenger or an obstacle (e.g., stowed item) happens to be in a second row seat when a memory module moves a front seat rearward to reset its seat position register, the seat may impact upon the passenger or damage the stowed item. In view of the foregoing, it may be appreciated that this attempted solution represents a safety problem.
All the same, OEMs and end users may have little option, since memory modules not incorporating “reset” technology may exhibit large and increasing positional errors. Of course, such positional errors may also be dangerous, and if nothing else, these accumulated positional errors may tend to result in user dissatisfaction.
It should perhaps be noted that, in the past, an alternative to the use of Hall-effect sensor and ripple-counting based systems may have been to use potentiometer based systems. Though such potentiometer based systems may not have accumulated positional errors in the same way, significant disadvantages of such systems may have been generally well documented. These disadvantages may include high cost, noise, large package size, and/or a resolution that is limited by analog to digital conversion.
In view of all of the foregoing, it may be desirable to eliminate and/or minimize these positional errors, and/or to mitigate their negative consequences, in Hall-effect sensor and ripple-counting based systems. It may also be desirable to provide a memory module system that is able to detect a mechanical stop or obstacle that is encountered by the driven component. Still further, it may be desirable to provide a technology which is equally applicable in improving the accuracy of Hall-effect and ripple-counting based systems.
Of course, it may also be desirable to provide a component position recording device that may be relatively inexpensive to manufacture, may be readily mass-produced, and/or one that may fits into a relatively small design envelope. It may also be desirable to provide such a system that is both highly reliable and cost effective.
Accordingly, it is an object of this invention to obviate or mitigate at least one of the above-mentioned disadvantages of the prior art.